Generally, people with hearing loss refer to those who cannot hear well enough to understand speech in normal everyday situations—that is, hearing-impaired people. Hearing loss can be categorized as mild, moderate, moderate-severe, severe, etc. according to severity.
There are several types of hearing loss: conductive hearing loss, sensorineural hearing loss, and mixed hearing loss. Hearing loss has multiple causes, including damage to the external ear canal, perforation of the eardrum, disruption of the ossicles, otitis externa, otitis media, ageing, congenital problems, genetics, exposure to noise, hyperthermia, medications, etc., which may be classified by the damage to the bone conduction and air conduction.
Hearing-impaired people face difficulties in hearing in everyday situations, and therefore, they need a hearing aid to compensate for hearing loss well enough. The hearing aid is a device that amplifies a speaking person's voice or ambient sound to help a person with hearing loss hear speech clearly and give them a natural experience of hearing.
Generally, a hearing aid includes a transmitter that collects a speaking person's voice or ambient sound and outputs it as an electrical signal, an amplifier that receives the signal output from the transmitter and rectifies and amplifies it, a receiver that converts the signal amplified by the amplifier into a sound wave and sends it to the ear of a person with hearing loss, and a battery that supplies electric power to the transmitter, receiver, and amplifier. There are many types of hearing aids, including box-type aids, behind-the-ear aids, eyeglass aids, in-the-ear aids, and, more recently, completely-in-the-canal aids, an enhanced version of the in-the-ear type, which are placed deep in the ear canal.
With conventional hearing aids, however, there is no way for the wearer to indicate that they can conduct a conversation as they hear voice from their surroundings by activating an ambient listening function on their hearing aid.
Example of efforts in this regard include the following: Korean Patent Publication No. 10-2011-010186.